Field of the Invention
The present invention is directed to a folding table and seating arrangement and more particularly to a folding table and seating structure having a lightweight frame and a folding-assist system.
Description of the Prior Art
In large multi-purpose rooms utilized at various times as dining rooms, meeting halls, dance areas, training rooms, classrooms and for other varied activities, it is often desirable that furniture having a flexible configuration be used. In particular, folding table and seating structures have proven to be useful and are utilized in schools for common areas, lunchrooms and for other applications. Such folding table and seating systems provide a smaller footprint when folded for storage and increase the flexibility for multiple uses of spaces. Examples of folding tables are shown for example in U.S. Pat. No. 2,771,937 to Wilson, U.S. Pat. No. 3,075,809 to Wilson, U.S. Pat. No. 3,099,480 to Wilson and U.S. Pat. No. 6,254,178 to Bue, all assigned to Sico, Inc., the Assignee of the present invention. Although such tables provide great flexibility, further improvements are possible.
Folding table and seating systems require a framework for supporting opposed table tops as well as benches or stools and are typically on casters. The weight of the folding table and seating systems produces forces that may vary during the folding and unfolding of such systems and may increase the effort required by workers during folding and unfolding. Therefore, such systems often utilize a folding-assist system to aid in the folding and unfolding process so that less effort is required from workers performing the folding and unfolding. Such folding-assist has generally been provided by torsion bars and/or pneumatic cylinders. The torsion bars have generally been inserted along a pivot axis of the legs and connect to the table frame. Although torsion bars may counteract some of the weight and gravity to lessen the effort required, torsion bars are expensive, relatively heavy and add weight. Torsion bars may require special mounting to the frame to ensure torque is applied. Moreover, a torsion bar usually includes a preset amount of torsion that is not adjusted, although the amount of torque may change throughout the range of folding motion of the table. Folding table and seating systems also utilize pneumatic cylinders, often referred to as gas springs, which provide a degree of folding-assist. However, gas springs have a limited force ratio, which is the force at full extension compared to the force at full compression. A typical force ratio for gas cylinders is about 1.5, which limits the ability to vary the force exerted during folding and unfolding to provide folding assist to cancel out forces of the table and provide controlled folding and unfolding. Moreover, such gas cylinders tend to suffer from leakage and lose some of the force exerted as they age. Therefore, it is common practice for such cylinders to be initially configured to provide greater force than is actually required in order to make up for the expected loss of force exerted due to gas leakage over time.
It can therefore be seen that a new and improved folding table and seating system is needed with an improved folding-assist system. Such a system should provide folding assist that does not diminish over the life of the folding table and seating system. Moreover, such a system should be lightweight and provide easy rotation between frame elements during folding and unfolding. A folding assist system should be tuned to provide folding-assist that increases and/or decreases during portions of the range of folding and unfolding motion where different folding assist force is needed. The framework should be easy to assemble and should eliminate torsion bars at rotational axes of the folding framework. The present invention addresses these as well as other problems associated with folding table and seating systems and their folding linkages.